<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        const map = new Map();
        map.set('a',1)
        map.set('b',2)
        map.set('c',3)

        for(const [key, value] of map){
            console.log(key,value)
            // a 1
            // b 2
            // c 3
        }

        console.log('map',map)
        console.log(map.has('a')) // true
    </script>
</body>
</html>